[Gluster-users] self healing with sharding

[Gandalf Corvotempesta]

2016-07-08 11:23 GMT+02:00 Kevin Lemonnier <lemonnierk at ulrar.net>:
> No, only the shards that were modified during the downtime of the node
> will need to be healed. It is MUCH quicker than healing the whole
> VM file without sharding, and shouldn't provoke a freez of the VM
> because of locking.

This is not clear to me, due to my low understanding of gluster.

Let's assume a 100GB virtual machine image (qcow2 or whatelse) with 64MB shards
One users does this: "touch /tmp/test" inside this virtual machine,
during the node downtime.
Gluster will "update" only the involved shard, right ?
Thus, when node comes back, only that single shard must be healed,
maybe a 64MB shard on a 100GB image.

Without sharding, a single "touch" would require the whole 100GB to be sharded ?

What happens to the virtual machine, during the shard healing? Only
files included in that shard are set as read-only? Or all files
included in that shard are hidden ?
What if a file is spread across multiple shards and one of these
shards need healing ?